Reproduction and Residue Accumulation in Black Ducks

Three sets of 15 pairs of black ducks (Anas rubripes) were given 0, 10, or 50 ppm toxaphene in a dry mash diet for a period of 19 months, which included two breeding seasons. Survival of adults was not affected, but the weights of treated males were depressed during the summer months. Egg production, fertility, hatchability, eggshell thickness, growth, and survival of young did not vary with toxaphene ingestion in either breeding season. However, the mean number of days required to complete a clutch was lower in birds fed toxaphene than in birds on the control diet. Clutches of hens fed 50 ppm toxaphene showed improved hatching success in the second year of the study. Carcass wet-weight (70% moisture) residues in adults and the young birds averaged from 50 to 100% of the dietary concentration (7% moisture); egg residues showed a similar trend. Carcass residues did not reflect those found in the livers or brains of the adults, which seldom exceeded 0.5 ppm. Toxaphene residues were found in the brain of only one 10 ppm bird, but were present in nearly all of the 50 ppm birds. Toxaphene residues were present in the liver all all birds ingesting toxaphene. •xaphene, a complex mixture of chlorinated camphenes, is the most widely ed chlorinated hydrocarbon insecticide in the United States (Andrelenas ·74). It has been used in the southern regions of the Unitd States on cotton and Ybeans for more than 30 years, and, with the phasing out of DDT, toxhene · s. use as a synergist with other chemicals· on such crops as com and ,its is increasing (von Rumker et al. 1975). In addition to agricultural applicans, toxaphene has been used in lakes as a fish poison (Hemphill 1954, :yhew 1959, Hooper and Fukano 1960), and Johnson et al. (1966) reported its ~sence in lake water nine years after treatment. Thus, vertebrates are exsed to toxaphene in both aquatic and terrestrial habitats and their response to ubiquitous chemical must be considered . . idress correspondence to Susan D. Haseltine, Patuxent Wildlife Research Center. LaureL MD 0090-4341!80/0009-0461 $02.20 © !980 Springer-Verlag New York Inc. I \U\\111111 \\Ill \Ill\ 1\11 \Ill 9284 462 Susan D. Haseltine era Aquatic invertebrates and fish accumulate toxaphene from the water (Terriere et a/. 1966) and tend to be sensitive to small amounts (Mayer et ai. 1975· Mayer and Mehrle 1977: Schimmel et al. 1977). Ferguson eta/. (1964) demonstrated the capacity of several species of fish for building up resistance tc toxaphene contamination if use of the pesticide was heavy in a watershed area; in certain populations, sizeable residues of toxaphene may accumulate all(j become available to birds and mammals higher on the aquatic food chain. Mammals (Lehman 1952; Claborn et al. 1962) and birds (Genelly and Rudd 1956a; Bush eta/. 19na, 1978) are able to metabolize toxaphene adequatel~ and tolerate steady ingestion of the chemical for periods of months withou serious effects except for altered cartilaginous structures (Page et a/. Im). One reported exception to this tolerance is the white pelican (Pelecanus erythrorhynchos); 50 ppm toxaphene in the diet for four to five weeks has beer associated with mortality in young birds of this species (Keith I966b). Another exception is the reported death of young waterfowl in a marsh foUowing toxaphene application (Hanson 1952). Because of these reports of mortality in young aquatic birds, because there is an indication of reproductive effects at 100 ppm toxaphene and higher in tht diet of galliform birds (GeneUy and Rudd 1956b), later supported by Arscott e1 al. (1976), and because toxaphene is a widespread pesticide in wintering wa terfowl habitat, a two-year study was initiated to assess the effects of dietar: concentrations of 10 and 50 ppm toxaphene on survival and reproduction o adult black ducks, on growth and survival of young black ducks, and on residut accumulation in both young and adult birds. Methods and Materials Young-of-the-year black ducks from a captive colony were paired and placed in 4.6 x 9.1 n outdoor pens in November 1975. Each pen was equipped with a water trough, a cylindrical nes box, and a feeder. In December 1975, IS pairs were placed on each of three experimental diets. Th. diet consisted of a commercial duck breeder mash containing 0. !0, or 50 ppm technical grad toxaphene (w/w) carried in propylene glycol (1% of the feed by weight). Breeder mash containe. 2.8 to 3.2% Ca. 0.5 to 0.6% inorganic Panda minimum of 750 I.U. vitamin D,. No additiona organochlorines were present at levels above 0.1 ppm. At 2, 7. 12. and 19 months after th• experiment began, all adults were weighed and a five ml blood sample was taken from each bird One control female died in January 1976 and was replaced with a hen of the same age. When adult died later in the study they were not replaced, but their mates were continued on treatment in orde: to obtain weight and residue accumulation data. Egg-laying began in March 1976: after the first egg was laid, all nests and females were checke• daily. Each egg laid by a hen was numbered, examined for cracks, and placed back in the nest box the third egg in each clutch was coUected for residue analysis and eggshell thickness measurement~ Any hen which abandoned her nest or had her brood die in the first week after hatching was alloweL to renest. and data from the second brood were utilized if the young survived. All clutches wen candled at two weeks of incubation, and infertility and dead embryos were noted. Males wer. removed from the pen at 21 days of incubation so they would not disturb the young, but they wer maintained on the treatment diet. After hatching, ducklings were brooded by the hens and fed commercial starter mash of the same toxaphene content as their parents. Starter mash contained to 1.2% Ca. 0.5 to 0.6% inorganic P, and a minimum of 5,000 I. U. vitamin D,. No organochlorin< chemicals except toxaphene were present at levels above 0.1 ppm. For eight weeks, a supplemen of amprolium-ethopabate (0.013%) was added to the starter mash to prevent coccidiosis. Ducklings remained with the hen until 12 weeks of age. At five days to one week of age, at tw• Toxaphene in Ducks 463 weeks, and every two weeks thereafter, broods were weighed. At two weeks. one duckling from each brood was sacrified for residue analysis; at 12 weeks all ducklings in the treatment broods and one bird from each control brood were sacrified and prepared for analysis. After the first reproductive season, drakes were again placed with hens, control broods removed, and the pairs maintained on treatment diets throughout the following winter. Reproduction began again in March 1977, and the same procedures were followed as in 1976. At the end of July, after all broods were at least seven weeks old, adult black ducks were sacrificed and their brains and livers excised, weighed, and frozen for residue analysis. For toxaphene analysis all carcasses were plucked, and beaks, extremities of wings and legs, and digestive tracts were removed. Carcasses were weighed, wrapped in aluminum foil, and frozen. EggsheU thickness was measured at the equator with a Starett 1010 M micrometer. Entire brains, livers, and blood-samples, and 10-g portions of homogenized carcasses and eggs were analyzed individually for toxaphene. Extraction, sample cleanup with F1orisil~. and silicic acid separation procedures, similar to those described by Cromartie et a/. ( 1975), were made on adult tissue and eggs. Blood samples and young carcasses were cleaned up by gel pem1eation chromatography by the method of Johnson eta/. (1976). except that column length was increased to 500 mm and solvent volume for lipid elution was increased to 175 ml. Toxaphene was quantified with a gas-liquid chromatograph (GC) with a "'Ni detector, automatic sampler, computing integrator, and a 1.83 m x 6.35 mm glass column packed with I.59t OV-17/1.95% QF-1 at 200°C. The detection limit was set at· 0.1 ppm. The average recovery from tissues spiked with 10 or 20 ppm of toxaphene was 113%. The data were not corrected for recovery. Because toxaphene is such a complex mixture of chlorinated camphenes. the components of which may be metabolized at different rates, and because many other chemicals may elute in the same fraction, it is difficult to accurately quantify toxaphene residues. Therefore, two methods were used for estimating toxaphene residues. The ftrst method measured the total area under the GC cilrve and compared this value to the total area under the standard toxaphene curve; the second method, commonJy used with samples from the field, measured onJy the area under two characteristic toxaphene peaks whose retention times were 1.4 and 1.8 in relation to 1.0 for p,p 'DDT and compared this area to the area of the same peaks in the toxaphene standard: In both cases the peak areas were measured from valley to valley. One-way analysis of variance with a Scheffe · s test for mean separation was used when possible for reproductive. weight, and residue data. Arcsin transformations were used on percentage data before analysis. Difference of k proportions and Kruskai-Wallis tests were run on discrete data when appropriate.